The course of many disease states is often reflected by elevated levels of specific blood proteins and other molecules. This phenomenon is typically utilized as a diagnostic tool to define the pathology and to follow the course of clinical treatment. In many instances, these specific blood proteins are directly or indirectly responsible for the primary and secondary manifestations of the disease process. "Autoimmune" diseases can be described as diseases characterized by circulating antibodies to endogenous substrates and tissue proteins required by the body for normal growth and maintenance. "Neoplastic" diseases are typically characterized by uncontrolled growth of an undifferentiated transformed cell line which evades or compromises the body's natural defense mechanisms by producing immunosupressive blocking factors, surface antigen masking components and/or growth regulator constituents. Specific compartmentalization of these pathological effectors (e.g., causitive agent) onto a biocompatible substrate is consistent with the restoration of "normal" body function by removal of the pathological effectors of the disease process.
The basic function of the organs, cells and molecules that comprise the immune system is to recognize and to eliminate from the body foreign substances. These foreign substances are eliminated by reaction between the foreign substance and antibodies which are formed in response to the substance. In general, this function is performed efficiently and without detriment to the host. However, in certain instances, disturbances can occur which can lead to pathogenic disorders such as, for example, an uncontrolled response (allergic disorders) or an abnormal response (autoimmune disease). The pathogenesis of both of these disorders is related directly or indirectly to the production of antibodies with cross reactivities to either environmental antigens (allergens) or self-antigens.
An autoimmune disease is a pathological condition arising when a host responds immunologically by production of antibodies with reactivity to a self-antigen. Autoimmunity can affect almost every part of the body, and generally involves a reaction between a self-antigen and an immunoglobulin (IgM or IgG) antibody. Representative autoimmune diseases can involve the thyroid, kidney, pancreas, neurons, gastric mucosa, adrenals, skin, red cells and synovial membranes as well as thyroglobulin, insulin, deoxyribonucleic acids and immunoglobulins.
For some types of autoimmune and neoplastic diseases, non-specific immunosuppressant treatments, such as whole body X-irradiation or the administration of cytotoxic drugs, have been used with limited success. The disadvantages of such treatment include the toxicity of the agents used, and the increased incidence of various cancers, especially lymphomas and reticulum cell sarcomas, following such therapy. In addition, the use of non-specific agents for chronic cellular suppression greatly increases the susceptibility of the patient to serious infection from environmental fungi, bacteria and viruses which under ordinary circumstances would not cause problems. The invention disclosed herein is specific in that it removes only the pathological effector or those groups of pathological effectors which are related to and responsible for the manifestations of a particular disease.
In viewing the prior art, one finds that most recently there have been generally two approaches to therapeutic treatments for autoimmune and/or neoplastic diseases. The first of these is to introduce a material into the patient which causes a specific type of immunological tolerance to be produced. This suppression of antibody response would then effect a tolerance to the offending antigen. A typical example of this type of approach is U.S. Pat. No. 4,222,907 issued to Katz on Sept. 16, 1981. In this disclosure, the diseased patient is given a therapeutic treatment which consists of introducing conjugates of an antigen linked to a D-glutamic acid: D-lysine copolymer.
The second approach has been the extracorporeal route. The procedures generally involve the removal of whole blood, separation of cellular and soluble blood substances, substitution or treatment of blood plasma and recombination-infusion of the treated whole blood. The first example of this approach would be plasma substitution or exchange with salt, sugar and/or protein solutions and is described by McCullough et al, "Therapeutic Plasma Exchange," Lab. Med. 12(12), p. 745 (1981). Plasma exchange is a rather crude technique that requires a large volume of replacement solution. A second example of this approach involves physical and/or biochemical modification of the plasma portion of whole blood. Typical of the state of the art of this therapeutic treatment are, for example, the Terman et al article "Extracorporeal Immunoadsorption: Initial Experience in Human Systemic Lupus Erythematosus," The Lancet, Oct. 20, 1979, pages 824-826. This article describes a hemodialysis type system utilizing two mechanical filters with a DNA collodian charcoal filter between said two mechanical filters. Typical of this state of the art, however, the adsorbant column is only semispecific for immune components because the charcoal substrate will non-specifically adsorb many vital low molecular weight constituents from the treated plasma. A second application of this approach can be illustrated by the Terman et al article "Specific Removal of Circulated Antigen by Means of Immunoadsorption," FEBS Letters, Vol. 61, No. 1, January, 1976, pages 59-62. This disclosure teaches the specific removal of radiolabeled antigen by antibody treated cellulosic membranes. The author, however, demonstrates that control membranes have a significant capacity to non-specifically adsorb proteins.
A third application of this approach is illustrated by the Bansal et al article "Ex vivo Removal of Serum IgG in a Patient With Colon Carcinoma," Cancer, 42(1), pp. 1-18 (1978). This report teaches the semi-specific adsorption of immunoglobulin by ex vivo treatment of plasma with formalin and heat-killed Staphylococcus aureas. The biological activity of certain strains of S. aureas is attributed to a molecule present on the cell wall, called Protein A, which interacts and binds with the Fc portion of mammalian IgG. This treatment, because it interacts with the Fc moiety, does not discriminate between normal and pathological IgG components and experiments have shown the possibility of significant side effects.
A fourth application of this approach can be illustrated by the Malchesky et al article "On-line Separation of Macromolecules by Membrane Filtration With Cryogelation," Artif. Organs 4:205, 1980. This publication teaches the semi-specific removal of cryoglobulin substances from plasma by the combination of filtration and cold treatment chambers. The incidence and composition of cryoglobular precipitates are not necessarily consistent with or indicative of many autoimmune or neoplastic diseases.
Another problem associated with the current state of the art is that without systems using mechanical filtration, the specific pathological effectors desired to be removed have not been removed in large enough amounts to do much good for the diseased patient in that the columns do not specifically adsorb substantially only the desired specific pathological effectors.
It has now been found that high specificity of pathological effector removal can be effectuated by treatment of blood and/or plasma in an economical manner using the present invention.